Since 1.72 on main (stable) branch, as squad leader in a vehicle, I have been seeing this odd thing quite often lately, no mods loaded. After selecting all crew members, or just the driver, when I point to somewhere on the terrain and select "Move to," I hear the voice command "Move to grid 000000." AI driver doesn't know what to do, and the command often repeats, even after I order driver to stop.
Once crew is ordered to disembark, and then to get back in, the problem doesn't occur any longer, I think. The issue may only occur when mission (in editor or from a savegame) is started with player in a vehicle as squad leader.